管理NSNotification以及UITabBarController交互 [英] Managing NSNotification along with UITabBarController interactions

问题描述

我有1个主UIViewController，其中包含一个UITabBarController.标签栏控制器具有4个UIViewControllers(每个UIViewControllers由UINavigationControllers管理).简而言之，它看起来像这样:

I have 1 main UIViewController that contains a UITabBarController. The tab bar controller has 4 UIViewControllers (each managed by UINavigationControllers). Succinctly, it looks like this:

MainViewController
   |
   |--- FirstUIViewController
   |
   |--- SecondUIViewController
   |
   |--- ThirdUIViewController
   |
   |--- FourthUIViewController

默认情况下，FirstUIViewController已加载.

The FirstUIViewController is loaded by default.

在SecondUIViewController中，可能发生一个事件.此事件具有与之一起传递的特定数据.当此事件发生时，我希望发生两件事:

In the SecondUIViewController, there is an event that can occur. This event has specific data that is passed along with it. When this event occurs I want 2 things to happen:

1)已在选项卡栏控制器中选择"FourthUIUIViewController"以直观地显示另一个选项卡.

1) FourthUIViewController to be selected in the tab bar controller to visually show a different tab has been entered.

2)在ThirdUIViewController中的后续操作，其中选择了特定的UITableViewCell.所选单元格由事件中传递的数据确定.

2) A subsequent action in FourthUIViewController where a specific UITableViewCell is selected. The selected cell is determined by the data that is passed along in the event.

为此，我在MainViewController中创建了一个NSNotification观察器.它从SecondUIViewController监听事件，并通过userInfo从事件中获取数据.

In order to do this, I've created an NSNotification observer in the MainViewController. It listens for the event from the SecondUIViewController and gets data from it via userInfo.

我也知道从MainViewController可以轻松地在UITabBarController上设置selectedIndex，以便显示正确的选项卡. (排名第一).

I also know that from MainViewController I can easily set the selectedIndex on the UITabBarController in order to have the correct tab shown. (#1 accomplished).

但是，完成#2令我感到困惑.我不知道如何(正确地，正确地)设置选项卡栏的selectedIndex，然后让FourthUiViewController对选定的单元格起作用.我的假设是，在此事件发生之前可能尚未加载FourthUIViewController，因此我无法设置任何参数或调用任何观察者.

However, accomplishing #2 baffles me. I don't know how to (properly, correctly) set the selectedIndex of the tab bar and then have the FourthUiViewController act upon a selected cell. My assumption is that FourthUIViewController may not have been loaded before this event occurs so I couldn't set any parameters or call any observers.

也许更广泛的问题是通过选项卡选择加载UIViewController时如何传递数据(与推送一个非常简单的新UIViewController相比).

Perhaps the broader question is how data can be passed when loading a UIViewController through tab selection (compared to pushing a new UIViewController which is very straightforward).

TIA.

推荐答案

视图 controller 将始终在启动时加载，除非您对NIB文件做了非常奇怪的事情.

The view controller will always be loaded at startup, unless you've done something very weird with your NIB file.

可能未加载控制器的视图，但是您可以在操作该视图的视图之前调用[fourthController view](或者，如果合适，[self view])来强制执行该操作桌子.

It's possible that the controller's view won't have been loaded, but you can force that to happen by calling [fourthController view] (or, if appropriate, [self view]) before you manipulate that view's table.

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